1. Field of the Invention
The present invention relates generally to a satellite receiver system, and in particular, to a method and apparatus for connecting satellite receiver modems over coaxial cable.
2. Description of the Related Art
Satellite broadcasting of communications signals has become commonplace. Satellite distribution of commercial signals for use in television programming currently utilizes multiple feedhorns on a single Outdoor Unit (ODU) which supply signals to up to four IRDs on separate cables from a multiswitch.
FIG. 1 illustrates a typical satellite television installation of the related art.
System 100 uses signals sent from Satellite A (SatA) 102, Satellite B (SatB) 104, and Satellite C (SatC) 106 that are directly broadcast to an Outdoor Unit (ODU) 108 that is typically attached to the outside of a house 110. ODU 108 receives these signals and sends the+ received signals to IRD 112, which decodes the signals and separates the signals into viewer channels, which are then passed to television 114 for viewing by a user.
Satellite uplink signals 116 are transmitted by an uplink facility 118 to the satellites 102-104 that are typically in geosynchronous orbit. Satellites 102-106 amplify and rebroadcast the uplink signals 116, through transponders located on the satellite, as downlink signals 120. Depending on the satellite 102-106 antenna pattern, the downlink signals 120 are directed towards geographic areas for reception by the ODU 108.
Each satellite 102-106 broadcasts downlink signals 120 in thirty-two (32) different frequencies, which are licensed to various users for broadcasting of programming, which can be audio, video, or data signals, or any combination. These signals are typically located in the Ku-band of frequencies, i.e., 11-18 GHz. Future satellites will likely broadcast in the Ka-band of frequencies, i.e., 18-40 GHz, but typically 20-30 kHz.
FIG. 2 illustrates a typical ODU of the related art.
ODU 108 typically uses reflector dish 122 and feedhom assembly 124 to receive and direct downlink signals 120 onto feedhom assembly 124. Reflector dish 122 and feedhom assembly 124 are typically mounted on bracket 126 and attached to a structure for stable mounting. Feedhorn assembly 124 typically comprises one or more Low Noise Block converters 128, which are connected via wires or coaxial cables to a multiswitch, which can be located within feedhom assembly 124, elsewhere on the ODU 108, or within house 110. LNBs typically downconvert the Ku-band and Ka-band downlink signals 120 into frequencies that are easily transmitted by wire or cable, which are typically in the L-band of frequencies, which typically ranges from 950 MHz to 2150 MHz. This downconversion makes it possible to distribute the signals within a home using standard coaxial cables.
The multiswitch enables system 100 to selectively switch the signals from SatA 102, SatB 104, and SatC 106, and deliver these signals via cables 124 to each of the IRDs 112A-D located within house 110. Typically, the multiswitch is a five-input, four-output (5×4) multiswitch, but can also be a 6×8 multiswitch, where two inputs to the multiswitch are from SatA 102, two inputs to the multiswitch are from SatB 104, and one input to the multiswitch is from SatC 106. SatC 106 typically delivers local programming to specified geographic areas.
To maximize the available bandwidth in the Ku-band of downlink signals 120, each broadcast frequency is further divided into polarizations. Each LNB 128 can only receive one polarization at time, so by aligning polarizations between the downlink polarization and the LNB 128 polarization, downlink signals 120 can be selectively filtered out from travelling through the system 100 to each IRD 112A-D.
IRDs 112A-D use a one-way communications system to control the multiswitch. Each IRD 112A-D has a dedicated cable 124 connected directly to the multiswitch, and each IRD independently places a voltage and signal combination on the dedicated cable to program the multiswitch. For example, IRD 112A may wish to view a signal that is provided by SatA 102. To receive that signal, IRD 112A sends a voltage/tone signal on the dedicated cable back to the multiswitch, and the multiswitch delivers the satA 102 signal to IRD 112A on dedicated cable 124. IRD 112B independently controls the output port that IRD 112B is coupled to, and thus may deliver a different voltage/tone signal to the multiswitch. The voltage/tone signal typically comprises a 13 Volts DC (VDC) or 18 VDC signal, with or without a 22 kHz tone superimposed on the DC signal. 13 VDC without the 22 kHz tone would select one port, 13 VDC with the 22 kHz tone would select another port of the multiswitch, etc. The voltage/tone signal can also be a modulated tone with a voltage, such that more than four ports can be used and uniquely selected.
Further, some of the programs that are broadcast by SatA 102, SatB 104, and SatC 106 are “pay-per-view” programs, that are enabled and disabled through programming of the IRD 112. Typically, a customer will use a remote control to program the IRD 112, which then places a phone call to a customer service control point to enable a specific IRD 112 to decode the signals present on the pay-per-view channel.
Further, in some installations, each IRD 112 must be coupled to a phone line to enforce contractual blackout requirements, or for security reasons to assist in locating the IRD 112.
However, such services require that at least one, and possibly all of the IRDs 112 be installed physically proximate to the subscriber's television set and also require that the IRD 112 be installed such that a telephone line can be connected to the IRD 112. In some installations, new telephone lines must be run to the location within house 110 where the IRD 112 is located for the pay-per-view service to be activated. This increases the complexity and the cost of IRD 112 installation, and, in some circumstances, make it impossible to install an IRD 112 in a desired location because of the difficulty of running a telephone line to the desired location.
Other attempts at using internal house power lines to distribute telephone signals have been proposed, but the bandwidth of these systems cannot handle the other requirements that are necessary for the integration of satellite signal system distribution with such systems.
It can be seen, then, that there is a need in the art for a satellite broadcast system that can be easily installed in any location in a home. It can also be seen that there is a need in the art for a satellite broadcast system that utilizes pre-existing household telephone wiring to minimize cost and increase flexibility in arrangement of the system components.